TY - JOUR
T1 - Phase stability, structures and properties of the (Bi-2)(m) (Bi2Te3)(n) natural superlattices
AU - Bos, J. -W. G.
AU - Faucheux, Francois P
AU - Downie, R. A.
AU - Marcinkova, A.
PY - 2012/9
Y1 - 2012/9
N2 - The phase stability of the (Bi-2)(m) (Bi2Te3)(n) natural superlattices has been investigated through the low temperature solid state synthesis of a number of new binary BixTe1-x compositions. Powder X-ray diffraction revealed that an infinitely adaptive series forms for 0.44 <= x <= 0.70, while an unusual 2-phase region with continuously changing compositions is observed for 0.41 <= x <= 0.43. For x > 0.70, mixtures of elemental Bi and an almost constant composition (Bi-2)(m) (Bi2Te3)(n) phase are observed. Rietveld analysis of synchrotron X-ray powder diffraction data collected on Bi2Te (m=2, n=1) revealed substantial interchange of Bi and Te between Bi-2 and Bi2Te3 blocks, demonstrating that the block compositions are variable. All investigated phase pure compositions are degenerate semiconductors with low residual resistivity ratios and moderate positive magnetoresistances (R/R-0 = 1.05 in 9 T). The maximum Seebeck coefficient is +80 mu V K-1 for x=0.63, leading to an estimated thermoelectric figure of merit, zT=0.2 at 250 K. (C) 2012 Elsevier Inc. All rights reserved.
AB - The phase stability of the (Bi-2)(m) (Bi2Te3)(n) natural superlattices has been investigated through the low temperature solid state synthesis of a number of new binary BixTe1-x compositions. Powder X-ray diffraction revealed that an infinitely adaptive series forms for 0.44 <= x <= 0.70, while an unusual 2-phase region with continuously changing compositions is observed for 0.41 <= x <= 0.43. For x > 0.70, mixtures of elemental Bi and an almost constant composition (Bi-2)(m) (Bi2Te3)(n) phase are observed. Rietveld analysis of synchrotron X-ray powder diffraction data collected on Bi2Te (m=2, n=1) revealed substantial interchange of Bi and Te between Bi-2 and Bi2Te3 blocks, demonstrating that the block compositions are variable. All investigated phase pure compositions are degenerate semiconductors with low residual resistivity ratios and moderate positive magnetoresistances (R/R-0 = 1.05 in 9 T). The maximum Seebeck coefficient is +80 mu V K-1 for x=0.63, leading to an estimated thermoelectric figure of merit, zT=0.2 at 250 K. (C) 2012 Elsevier Inc. All rights reserved.
U2 - 10.1016/j.jssc.2012.03.034
DO - 10.1016/j.jssc.2012.03.034
M3 - Article
SN - 0022-4596
VL - 193
SP - 13
EP - 18
JO - Journal of Solid State Chemistry
JF - Journal of Solid State Chemistry
ER -